Creatine (N-(aminoiminomethyl)-N-methyl glycine) is a nitrogenous organic acid which has a solubility of about 1 gram in 75 milliliters of water (about 13.3 g/L). Creatine has become one of the most popular supplements available in the sports nutrition market. In its solid form, creatine monohydrate powder is very stable, showing no signs of degradation over years, even at elevated temperatures. However, its use in liquid formulations, such as sports nutrition drinks, for example, has been limited by its low solubility and its decreased stability in solution. Creatine solubility may be increased at lower pH and higher temperatures, but at lower pH and at higher temperatures, creatine rapidly self-cyclizes into creatinine.
About 95% of the creatine in the human body is found in the muscle tissue. Because creatine plays a significant role in muscle metabolism, it is a popular supplement for athletes. It has also been suggested to have beneficial effects for disease conditions such as heart disease, chronic obstructive pulmonary disease (COPD), and Parkinson's disease.
One attempt to make a more soluble form of creatine has been described in U.S. Patent Publication Number 2011/0251280A1 (J. Owoc, now U.S. Pat. No. 8,445,466), which discloses the synthesis of amide-protected creatine molecules, generally formed by synthesizing peptides such as creatyl-L-glutamine.
Powdered drink mix sales have reached approximately one billion dollars per year. Their attractiveness is due, in part, because they can be available to consumers in canister-type containers, in single-shot sleeves, often referred to as “sticks,” in cap-mounted delivery systems, or in tablet form, for example. In these forms, the mixes may be carried by the consumer in a pocket, purse, gym bag, briefcase, lunchbox, or even a pocket. Creatine has typically not been a suitable ingredient for many of these formulations because it is not sufficiently soluble to be readily mixed to form a solution from a powder mix. Therefore, what are needed are compositions and methods for providing creatine in a more soluble form.